Audacity is a free, open source digital audio editor and recording application. Edit your sounds using cut, copy, and paste features (with unlimited undo functionality), mix tracks, or apply effects to your recordings. The program also has a built-in amplitude-envelope editor, a customizable spectrogram mode, and a frequency-analysis window for audio-analysis applications. Built-in effects include bass boost, wah wah, and noise removal, and the program also supports VST plug-in effects.